Development of Three Way Catalyst Aging Model: Application to Real Driving Emission Condition

Further reduction of vehicles pollutant and CO2 emissions is required to prevent global warming and to improve air quality. The exhaust system is designed to ensure low emission during all life of the vehicle. As catalyst aging is affecting the catalyst performance, such impact needs to be consider upfront during the design of the fresh catalyst. Until now, the exhaust system design are evaluated based on real tests for each vehicle, using exhaust lines aged on engine test benches or burner benches. This induces major investigation limitations such as: late evaluation in development cycle, high testing and prototyping cost. The usage of Model Based Development approach can be a powerful way to improve this process by allowing system evaluation under several aging conditions at early development stage. The present study focuses on modelling of the Three Way Catalyst (TWC) aging to predict the mileage impact on tailpipe emissions. The activity was divided in 4 steps: 1- Development of a detailed TWC for 4 different aging levels. The impact of aging is considered by tuning the pre-exponential factors of the reactions Arrhenius laws. The activation energies are not modified, since they are representative of the active site type. 2- Aging model development: aging laws are extracted from previous calibrated model considering reaction groups (oxidation, NO reduction, Oxygen Storage Capacity (OSC)…) and Platinum Group Metal (PGM) type. 3- Model validation on driving cycle: The tailpipe emissions are predicted with less than 15% deviation on WLTC. 4- Application and validation to another TWC technology (different amount of PGM and OSC): in that case also, the aged TWC emissions prediction is within 15% deviation on WLTC. The proposed aging model provides the possibility to predict aging of any TWC using same washcoat family, based on existing TWC model calibrated in fresh condition.